Moistureproofing composition



Patented Jan. 2?, 134% amps;

morsruanraoorma comosrrro William H. Bryce, Memphis, Tenn.. assignmtoDixie Wax Paper Company, DallaaTex.

No Drawing. Application February Serial No. 258.102 'LClainis. (oi.zoo-m) An object of my invention is to provide a novel coating compoundfor coating papers used for wrapping bread and other products.

' Another object of my invention i to provide a coating compound whichwill render a paper for wrapping bread moisture-vapor-prootand pliable.

A further object of my invention is to provide a compound which willmelt and liquefy below the boiling point of water without requiring theuse of any solvent, and in which a sheet of paper may be easily dipped.

A still further object of my invention is to procracking. Certain rubberderivatives are among the substances which I so employ.

Preferably, I start, with a particular type glassine paper wherein therehas been incorporated during manufacture particular substancesto'enhance its desirable physical characteristics.

. A first group of substances so applied may invide a wrapping paper forwrapping bread and other products which has a coating ofa wax compoundwhich is moisture-vapor-proof, but which coating is still not of suchexcessive thickness a to crack when bent and thereby render the paperopaque.

Yet another object of my invention is to provide a highly plasticizedpaper for wrapping candyand other products which will retain its twistedcondition when used for twisting around pieces of candy and the like.

' In the wrapping of bread and various other food products, and otherarticles, glassine paper is often used, and the present invention isparticularly concerned with such glassine paper. Glassine paper isusually produced by long continued beating of pulp followed bysuper-calendering, andis highly transparent. Glassine pulp is highlygelatinized.

Ordinary glassine paper usually is given a thin coating of wax which isapplied thereto to increase its degree of water-proofness andtransparency. However, glassine paper even so treated is not entirelyimpervious to water vapor, and

creasing the transparency of the paper, leaving a tacky surface, and inhot weather or under elevated temperatures, such a wax coating will run.Further, a thick coating of wax will crack when bent or folded, leavingvisible creases.

crease transparency of the paper.

I provide a glassine paper which is treated ,with particular substanceswhich render it substantially moisture-vapor-proof, and at the same timehighly plastic. so that it may be bent without elude small percentagesof a mild alkali like sodium metasilicate, or cerelose or invert orequivalent special sugar, or both. A second group of substances whichmay be so applied may include glycerine, glycol, magnesium chloride orzinc chloride; I use relatively more of this second group than of thefirst group, and ordinarily em. ploy more of the glycerine than theother substances mentioned. A liquid containing one or more of thesesubstances may be applied to the glassine paper' sheet when near the endof its usual proces of manufacture and partially dried,

but still holding a considerable percentage of moisture. The mild alkalitends to increase the sheen. The cerelose improves the transparency,gloss, and moisture-proofness. The glycerine, glycol, magnesium chlorideor zinc chloride are hygroscopic, and very considerably increase thepliability and the elasticity in tension; and make the paper highlyplasticized.

I take glassine paper preferably of the particular type which has beendescribed, and which has been highly plasticized, and apply thereto-athin layer of a meltable, waxy substance which .not only renders .theglassine paper moisturevapor-proof, but also imparts desirable heatsealing qualities.

A preferable way to make this waxy composition is to melt some suitablewax such as a good grade of parafiln or beeswax, or the like, anddissolve therein a relatively low percentage of a suitable rubberderivative. Such waxes and the type of rubber derivatives hereindescribed blend satisfactorily in all proportion under such a meltingprocess without a solvent. Preferably, I

On the other hand, a thin coating of wax tends to inuse a highpercentage of wax, in order to make the coated papermoisture-vapor-proof.

A rubber derivative suitable for this purpose is the substance known asplio1ite" resin which is a resinous rubber addition product compound ofthe kind obtained by treating rubber with a compound of the type ofhydrated chloro-stannic acid and precipitating the product in a finelydivided state which is easily dissolved in wax; similar "pliolite resinderivative are formed by treating rubber with a halide of an amphotericmetal. This type of rubber resin contains about by weight of rubberhydrocarbon, and in the aggre- -.3000. This does not emulaiiy.

about 3% mineral oil, but in some cases m y gate is amber in color. Thereaction polymerises the rubber. Such compounds are described, forinstance, in the Bruson Patent 1.8486347. It is substances oi this typewhich I hereafter refer to as "pliolite." I use the unmilled "pliolite"resin in powdered iorm.

This "pliolite" resin blends with the wax in all proportions. I

In one iorm (Formula. A) of my meltable, compound i'or coating theglassine paper, Iadd a small quantity oi a hydrogenated or polymerizedodorless fat or oil with a melting point over 130 R, such ashydrogenated cotton-seed oil, as

a lubricant to facilitate handling oi the paper during manufacture.while I have in this tormula indicated 10% hydrogenated cottonseed 011.

this percentage may be increased or diminished within allowable limitsaccording to lubrication conditions to be met. The hydrogenatedcottonseed oil employed should be a highly purified grade, tree fromobjectionable odors. The commercially available product has a meltingpoint oi about 130 F. Instead oi hydrogenated cottonseed oil, I may alsoemploy hydrogenated soybeen all or hydrogenated castor oil.

I also add a small quantity or diamyl naphthalene to improve theadhesive properties of the paper under applied heat.

For certain purposes. I may also add a fewpercent of tricresyl phosphate("LindoPi which acts as a plasticizer and imparts other desirablequalities.

In an improved modified form or my coating compound. (Formula B), Iincorporate substantial quantities of ester gum. and also a heavy.sticky mineral oil. A suitable ester gum is rosin glyceride. A suitableoil is the product furnished by Vacuum Oil 00. under the designation P.O. I usually use use as high as 15% mineral oil. The ester gum preventswilting or mottling or the glassine paper and makes it moremolsture-vapor-prooi. The ester gum also reduces the crystallinlty orthe waxy compound and makes it more transparent and harder. The estergum is too brittle it applied alone without wax.

In the melt described, the ester gum will'precipitate in the absenceoi'the mineral oil which acts as a plasticizer, and hence the ester gumwill be oi little use. but in the presence of the plastieizer mineraloil. the ester gum will iorm a part of the melt. The ester gum ispreferable to dammar or cumar gums, which I have also tried for thispurpose. The wax with incorporated rubber resin, when melted, has stilla sumoiently low viscosity so that a sheet or paper may be convenientlydipped therein. This would remain true even it relatively largepercentages oi rubber resin were used, but ordinarily, I use only about5 to of rubber resin.

Besides the uses oi diamyl naphthalene and trlcresyi phosphate as abovementioned, they also serve as plasticisersio prevent the ester gum fromdrying out or oxidizing out or the solution, and forming on the sides oithe tank or the squeeze rolls.

While ingredients similar to some of those mentioned have beenheretoiore used in coating solutions for paper, they have been used insuch a way as to require expensive solvents such as toluol and the liketo get them into the liquid phase. I avoid theuse'oi these expensivesolvents by employing substances which when melted will all pass intothe liquid-phase.

One iormula which I have employed with suc- I cessis:

' Formula A Percent 5 "Pliolite" resin (powdered).. l5 Hydrogenatedcottonseed oil 10 Diamyl naphthalene 2% Paraiiin wax 83% lo Total 100Asstated,thewax maybeparaiiimbeeswax. or other vegetable or animal waxesor similar characteristics.

An improved iormula which I have iound more satisfactory in practice iorgeneral application is:

Formula 8 Percent "Pllolite" resin (powdered) 4 n Hydrogenated iatmelting above 130' I"...... 5 Dlamyl naphthalene 1 Ester gum 18 Heavysticky mineral oil 8 Paramn wax 66 Total 100 This improved "Formula. 3."as stated, gives a product much less susceptible to wilting. and whichis more moisture-vapor-proor.

The coating according to either "Formula A" or "Formula B" will melt attemperatures of about 175 F. to 200 1'. and liqueiy without the use atany solvent. The melt has a low viscosity.

A iormula which I employ for low temperature or winter conditions is:

Formula C Percent Pliolite" resin (powdered) 6 w Hydrogenated iatmelting above 130' IL... 5 Diamyi naphthalene 1 'I'ricresyl phosphate 1Ester gum ii Heavy sticky mineral oil 8 M Paraflln wax 79 Total 100 Forrelatively warm temperatures or summer conditions. I had the i'ollowinga desirable ior mule:

Formula D Percent Pliolite" resin (powdered) a Hydrogenated iat meltingabove 130' P... 15

as Diamyl naphthalene 1 'Iricresyl phosphate 1 Ester gum 15 Heavy stickymineral oil 8 Parailin wax 59 Total 100 For conditions under which thewrapper must be particularly grease-proof, the iollowing is desirable:

a Formula 8' r P t Plio1ite" resin (powdered) jf e Hydrogenated latmelting above 130 PL..- 40

Dlamyl naphthalene "I 1 ricrcsyl phosphate 2 Ester gum 40 Heavy stickymineral oil 3 Parailln wax 10 Total In this formula, the 40% ofhydrogenated cottonseed oil or other hydrogenated fat impartsgrease-proofing qualities.

Under some conditions, as if a particularly good permanent seal is notimportant, it is possible to omit the "pliolite" resin and get fairlysatisfactory results employing the following formula:

Formula F Percent Hydrogenated fat melting above 130 IL--- 40 Diainylnaphthalene 1 Tricresyl phosphate 2 Ester gum 42 Heavy sticky mineraloil -L Paramn wax Total 100 This Formula F will produce a sheet which isheat-sealing, but it does not stay sealed for a length of time as willpaper to which the "pliolite" formulas have been applied, but after afew days will unseal. However, Ihave found that sheets treated withFormula F may be made permanently heat-sealing by exuding on to one s:ie of the sheet a concentrated rubber liquid composition, after thesheets have left the squeezerollsafter the coating of Formula F has beenapplied thereto and is still in melted condition, and before the sheetstrikes the congealing rollers.

' A polishing roller smooths the composition on the sides. Also, themelt may be applied. to only one side of the paper by a roller, and tothe other side of the paper a'coating of an ordinary wax may be applied.

For application to both sides, four pounds or more of this hot melt isapplied to a ream of paper of 480 sheets of size 24 x 36 inches. Bestresults are obtained when applying about seven pounds of this melt to aream of paper.

Heretofore, there have been used certain coating compositions having avery large percentage of pliolite" and only a relatively smallpercentage of wax together with an expensive solvent like toluol; suchcompositions are necessarily expensive. On'the other hand, I provide acomposition with about 66% wax or more and only 4% or 5% pliolite,"and'no special solvent, which is much less expensive.

The glassine paper treated with this hot melt is flexible, non-tacky,glossy, and moisture-vapor-resistant, and thermoplastic or adhesive. Thetreated paper also has increased tensile strength and is more resistantto the action of light and heat than the untreated paper, and is moretransparent. The treated paper is tasteless, odorless, and non-toxic.The high degree of imperviousness to moisture-vapor produced makes theproduct which I have described, particularly suitable for wrappers forbread andother food products. After the treated paper has been wrappedaround a food product as bread, it is heat-sealed by momentarilyvapplying to overlapping edges by a sealing hot plate, a temperature ofabout 175 to 200 F. which liquefles the melt including the dispersedplioli and the melted "pliolite on the two surfaces causes them to weldand seal tightly.

I have found the product which I have described to be very satisfactoryin application and use. and to have decided advantages over previouscompounds intended for similar purposes. I claim:

1. A meltable wax-like composition containing from 4 to 6 percent of apowdered resinous rubber derivative, hydrogenated fat melting above 130F., and upwards of 59 percent of a wax, said rubber derivative being theresultant of treatin rubber with a halide of an amphoteric metal.

2. A meltable wax-like composition having the formula Per cent Resinousreaction product of rubber andan amphoteric metal halidev compound(powdered) Hydrogenated fat melting above 130 F. 5 'Diamyl naphthalene 1Tricresyl phosphate 1 Ester gum 5 Heavy sticky mineral oil 3 Parafllnwax '79 Total 100 3. A meltable wax-like-composition having the formulaPer cent Resinous reaction product of rubber and an amphoteric metalhalide compound (powdered) 6 Hydrogenated fat melting above 130 F 15Diamyl naphthalene w 1 Tricresyl phosphate 1 Ester gum 15 Heavy stickymineral oil 3 Paraffin wax 59 Total 4. A meltable wax-like compositionhaving the formula Per cent Resinous reaction product of rubber and anamphoteric metal halide compound (powdered) Hydrogenated fat meltingabove F 40 Diamyl naphthalene 1 Tricresyl phosphate 2 Ester gum 40 Heavysticky mineral oil 3 Paramn wax 10 Total 100 sealing means.

6. A wax-like composition for coating papers containing a largepercentage of paraffin wax, an

unemulsified heavy mineral oil, .and a low percentage of an unmilledthermoplastic resinous powder prepared by treating rubber with a halideof an amphoterie metal.

7. A wax-like composition for coating papers WILLIAM H. BRYCE.

